1. Field of the Invention
The present invention relates to a light resistant polymer film, to an ultraviolet absorber and a merocyanine compound useful for preparing the polymer film or the like, and to a novel process for preparing merocyanine compounds.
2. Background Art
For attaining ultraviolet absorption ability, adding an ultraviolet absorber to a polymer film such as a protective film has been known. For example, the polymer film containing a merocyanine compound as an ultraviolet absorber is disclosed in JP-A-8-239509. And, in JP-A-2009-67973, there has been proposed a polymer material containing, as an ultraviolet-absorbing agent, a merocyanine compound, and also proposed a molded article, coated-ultraviolet absorbing layer or the like prepared by using the polymer material. And in JP-A-2009-64006 and JP-A-2009-64007, using a merocyanine compound as a wavelength-dispersing agent for polymer films has been also proposed.
On the other hand, conventional merocyanine-series ultraviolet absorbers don't have sufficient light-fastness, and it is known that their ultraviolet-absorbing abilities decrease over time. For example, in JP-A-2009-270062, for improving light-fastness, using another ultraviolet absorber along with the merocyanine-series ultraviolet absorber has been proposed.
The process for preparing the mecrocyanine compound is disclosed in JP-A-2003-277349.